Concrete shell design has become quite popular, but the complexities of forming these structures have often resulted in uneconomic solutions.
Various schemes for the economic construction of concrete shells employing inflatable forms have been presented. Most of these schemes employ a single, large air filled balloon as the forming vehicle.
This solution has two apparent faults.
1. The air in such a balloon, since it is readily compressed, would have to be at a high pressure in order to withstand the combined weight of the concrete and steel reinforcing members.
2. The single large balloon would seem to have only limited potential for reuse since there is no way to introduce design differentiation into the final product without fabricating a completely new balloon.
This invention offers a solution to the problems cited above. The basis of this invention relies on the fact that water is a virtually incompressible fluid that takes the shape of its container and unless that container is rigid, is subject to distortion. This invention utilizes water filled bladders of sufficiently small dimension such that when the bladders are laid up in an overlapping and interlocking "building block" fashion, the weight of the water and the restraining characteristics of the fabric in the bladders create a stable mold that is capable of supporting a concrete shell while undergoing a minimum of distortion. The water filled bladders could be manufactured in several different sizes so that when a plurality of such bladders was aggregated, the design possibilities for the resultant mold would be limitless. The utilization of such a concrete shell forming technique could have significant implications for the housing industry since relatively low cost structures could be fabricated which would preserve freedom of design while employing relatively unskilled labor.